Side blast firepot shape/fire shape?

[Exo313]

Given parameters below, what's the best way to build my fire, its firepot, or both for effective fuel consumption? 

Fuel: charcoal.

Stock size: 1/2 round or square, maximum.

Orientation: side blast

Heat desired: 3-4" max.

Wanting to make: small trinkets, nails, hooks, pendants, etc. 

Air supply: as yet undetermined, can build or buy to suit.

I've been doing some reading and observed some demos. Seen everything from JABOD style holes in a clay substrate, to simply piling charcoal up against a bellows stone.  

[JHCC]

Definitely go JABOD. Keep the firebowl on the small side, but don't sacrifice depth too much. Remember, you can always make a taller fire by adding firebricks around the bowl. Charcoal likes a gentle blast, so don't go overboard on your air supply.

[Charles R. Stevens]

The historical record indicates a 6" heat zone, and a 3/4-1" id Tuyere pipe for ironage charcoal forges. 

[Charles R. Stevens]

This is a shallow bowl about 6" across. The pile on top is some 8" across. Asians tended tord trenches, about 4" wide and 8" long. More effecent fuel use, more of a pain getting the stock in the heat zone. I use (and melt) hard fire brick, this allows me to shape the pile more effencently for the particular project. A fire bowl with strait sides fore and aft and sloped sides 4" wide buy 8" long may be more effect and cut down on brick melting. 

[Exo313]

I think the trench vs.  bowl is what was messing me up. 

[Charles R. Stevens]

The first and second box of dirt forges were based on a bowl. As noted the Asians use a trench, historicly probably two turmite mounds. My experiments lead me to combining the two, as with a trench and bricks I can make a pile for odd shapes (with or without one brick on the side) or even a furnace with bricks on the side and over the top. With dirt and a spoon you can experiment as to deapth, size and shape. 

[Frosty]

Exo: You're trying too hard to pin these things down there is NO standard sideblast forge. Sure there are companies that made thousands of them but every company made their own version. My advice to you is. Find or make a box large enough to experiment with different sizes and shapes. Pick a general shape, style, etc. flipping coins is an excellent way to choose, build one note what you like, don't like, don't understand, don'e care about. Then make another in that style but try something new and see if you can make the bad parts go away and the good parts get better. Stick with the same type for a while and use each version a couple times to get used to it. UNLESS it's such a horrible idea it scares the birds to death in the neighbor's tree!

Try a different type and repeat. This is just a box of dirt and you aren't doing anything that needs a spec sheet.

Frosty The Lucky.

[Exo313]

Frosty, you made me laugh out loud.  Not because you were being funny, but because due to your comments l was able to see the humor in my own actions. You're dead right.  I'm without a workspace right now so I'm armchairing at the moment. I'd done just enough tinkering at the in-laws to get bitten by the bug, but that situation is unavailable now. So I spend a lot of time reading and thinking about smithing. Or overthinking..

[Lou L]

I made the exact same mistake you are making but I don't regret it.  My armchair blacksmithing resulted in me amassing a load of actionable knowledge once I started melting my first projects.  I use a side blast design and have now gone through four iterations of the same forge.  First I changed the air source and the size of my fuel, trying all combinations of air and coal size.  Then JHCC inspired me to make some physical changes to my forge and firepot.  I just did another redesign today.  I now have a side blast (basically a steel JABOD) that is able to shed ash out of the bottom of the firepot.  I gave it a quick workout afterward and already have an alteration to do.  The best thing I have learned is what has already been explained above.  Just get a firepot of any size and shape and get it working.  All my planning for my forge turned out to be meaningless as I now use bricks to shape my firepot to my needs

 

Lou

[Charles R. Stevens]

Bingo. I did my reserch. As charcoal was to be my fuel of choice and coal has supplanted it in the west I looked at Asian, African and Viking/Iron Age forges. I also looked at English forges and asked our English brothers some ignorant questions. I also asked our resident civil war blacksmithing expert about cival war portable forges. 

After that I built a box, filled it with dirt and lit a fire. Dug trenches to lower the stock to the center of the fire ball and lit another fire. After more tweaking I built a second box and started again. I think I have learned enugh to build an other box. Need to buy another double action bed inflator and I have a nice 24" square and 12" deep steel box to build a portable tho a 24x36" bellows would be sweet

 

 

[ThomasPowers]

Hmmm I was just wondering about building a box bellows out of an ammo can as my scrapyard gave me some recently...

Learning blacksmithing has two major parts: That done with the  Brain and that done with a Hammer in your hand. Trying to do it all with only one method is like trying to win a foot race using only 1 leg.  You go MUCH faster using both!

[dimag]

I don't mean to hijack this thread but since we are talking about side blast charcoal forges.. I am building a trench style forge mounted on an old Canada Forge blower. It is configured to be a side blast and the fuel will be exclusively charcoal. It will be lined with firebricks backed by dura blanket. My question is; what is the minimum distance the tuyere can be off of the bottom?

[Lou L]

1 hour ago, dimag said:

I don't mean to hijack this thread but since we are talking about side blast charcoal forges.. I am building a trench style forge mounted on an old Canada Forge blower. It is configured to be a side blast and the fuel will be exclusively charcoal. It will be lined with firebricks backed by dura blanket. My question is; what is the minimum distance the tuyere can be off of the bottom?

I'm nowhere near the expert on this but my research and little experience tells me that "it depends".  The depths of your firepot matters.  You really want to be concerned with making sure the tuyere is on the bottom two thirds of the fire pot.  Mine is about 1.5" from the bottom... But my coal pile gets to 8-9" high at max.  I do not know if charcoal behaves differently enough to matter.  It certainly burns faster.

[Charles R. Stevens]

Dpends on the amount of silica in the charcoal, soft woods like pine, willow and adler produce light fluffy ash that will blow away wile Oak, maple, and hickory contain more silica and that ash will settle and have to be cleaned out once in a wile. I recommend 1" or so from the bottom of the bowl. This gives a space for ash and slag, yes you can get slag if your charcoal is dirty, made from scrap with nailes in it or you burn up some steel. 

Fire brick and blanket is overkill, 2" of brick or dirt will insulate wood on the bottom of your forge. Fire brick or nearly pure clay will prevent you from using coal in the future as the coal slag sticks like glue. I have melted hard brick uses to contain the coal above the bowl

as to shape and deapth, tuyere size and fuel size have something to do with it, for a 7/8" ID (schedual 40 3/4" pipe) about 3 1/2-4" above the tuyere works well a 8" wide at the top bowl is good, a 4" x 8" trench sloped at the long sides works very well, bricks on the sides are very usefull here to contain the fuel, even a brick over the top if one is only working strait stock, 

[dimag]

I have a coal forge but at $85 cad plus tax for a 70# bag it doesn't get used much. I also have a propane forge which gets used the most but the last quote I got to fill my 100# tank was $105 CAD plus tax. However ,I have a copious amount of wood on my property , so one can see why I am entertaining the use of charcoal and I am cheap.The firebrick I have is 1" so I thought the blanket ( which was free) would be needed. I have enclosed a photo or two of the mock up any ideas or criticism is very welcome.

[Charles R. Stevens]

Looks like your building a wood fired forge... But they work well too. What I would recomend is take a page from Frosty, find a suit inks table (your coal forge may work) pile dirt on it (2" will protect wood) and poke in a tuyer and build a fire. I can tell you what has worked historicly and for me, but your mileage may vary. First think like your coal forge, exept with a tuyere pipe coming in the side of the bowl not the bottom. Same basic idea with the table. 

 

[dimag]

I did build a Whitlox style forge for wood but I really did not like it. I make a lot of garden shepard's hooks of varying lengths and my thought was to get the length so I could bend the hook in one heat. The propane forge is just too small, it gets the job done but it take 2-3 heats. That is the main reason for the trench style. My other thought was that welding small stuff would be easier in this configuration. My forge welding skills are poor and I figured it would be better if I could pile the fuel up in a constricted area it might help. I will try this before I weld it up and see what happens. Most of the wood I have access to is aspen ,balsam poplar, spruce , pine and birch. So there shouldn't be a big accumulation of ash under the tuyere. 

[Lou L]

I think you are going to run into a complex air challenge with that design.  If you blast enough air to feed the area furthest from the tuyere it will likely be way too much for the area nearest it.  Because you are using charcoal it may be less of a problem but I can't imagine you will be getting anywhere close to even heat across that length.  

I have been thinking on this problem for a year now because I have a broken 5' plow I intend to turn into a trench style forge.  That latest design I've come up with involves a tuyere running the entire length with holes drilled every two inches.  I intend to encase the pipe in clay along the periphery of the fire pot leaving outlets (like small jets) that aim into the base of the fire pot along its length.

Because i haven't needed to heat more than 6" of stock at a time I haven't moved forward with my idea.  Honestly, the thin stock most of us work with (1/2" to 3/4") cools way too fast to work more than 6" at a time anyway.

[Charles R. Stevens]

Typically charcoal used a 3/4-1" tuyere, creating a 6" zone of working heat, to make a larger heat zone requires multiple tuyere. A Lively style forge just drills multiple holes in the side of the pipe. One can ofcorse move the stock back and forth to get a longer heat zone. For fuel efecency keep the fire small. I like being able to pass stock threw the fire, so don't go for the closed end, a trench 4" wide with a tuyere about evert 4" would work well, you could then just plug off the tuyere not needed, you will need about 4" of fuel under the stock so I would put a brick on each end to keep my fuel in. This then will give you a sword forge. 

 

[dimag]

Hmmm, it would seem I have not thought this through, as usual. Well, I guess I could run 1" pipe the full length of the box and drill holes in it, or, drill holes in the "air box".  I could also just go back to the drawing board.

[Charles R. Stevens]

A pipe down one side and a dit of Adobe mix to protect it would work, if one can find a pice of rod that fits the ID then one can block off the unused holes from the inside, square works as well, you could drill matching holes in the side, tack on a piece of square tube and mach up a square for the inside, I just don't love the bottom blast with charcoal. But that would be a nice set up with a sliding plate to contain the fuel at the with one needs

 

[Lou L]

Interesting idea with the square tubing.  Before I do it I need to do some tests to match the volume of the pipe, the air source and the number of jets.

I would likely use the design with coal and charcoal.  In the end, I may end up building a propane forge that can hear stock nearly as long and give up on the whole thing...

[Charles R. Stevens]

The problem with the gasser is that a long one waists a lot of fuel when you are doing 90% of your forging. 

[dimag]

Well I lit a fire today , I used a 1" nipple long enough to get about 1/3 of the way down the trench. I am sold on the side blast system! It seems to make controlling the charcoal fire so much easier than a bottom blast. Man, you sure don't need much air either. I used some maple lump charcoal, store bought, lots of fleas. Is it water in the charcoal that causes those sparks? I am going to use the forge the way it is for now till I get used to managing the fire better. I do have a idea for a manifold. My thought is to run the pipe down the outside  and tee it off three times. So there would be 3 1" tuyeres evenly spaced along the side. If they were threaded you could just cap or plug the ones you don't need. I still can't believe how little air you need to forge with this system!

[Charles R. Stevens]

Most commercial charcol isn't fully pyrolized a it makes a bit of smoke to impart to the smoke taste to food. That adds to the fire fleas, excess air adds to the problem. If you build a charcoal kiln, you can use thumb sized limbs and saplings as well as splits and building scraps.